Piston packing



@Spfn l w3. R. A. LIGHT ET AL.

PI STON PACKING Filed Sept. 8, 1934 l W1 TNESSES:

N INVENTORS:

HM ,E7/fi .Las

TTORNEYS.

Patented Sept. 17, 1935 PISTON PACKING Ralph A. Light, Cynwyd, and Joseph W. Price, Jr., Philadelphia, Pa., assignors to The United States Metallic Packing Company,

Philadelphia, Pa., a corporation of Pennsylvania Application September 8, 1934, Serial No. 743,188

4 Claims.

This invention relates to piston packings, and more particularly to a packing, for locomotive power reversegears, such as forms the subjectmatter of a co-pending application for patent L5 filed by us the 24th day of July, 1933, under YSerial Number 681,917, and which later matured as U. S. Patent No. 1,982,614, dated November 27, 1934.

In the application referred to, the sealing ring and the packing material are located ina circumferential groove formed jointly .by bull and follower rings which, in turn, are secured to a peripheral shoulder around the piston body member.

I'he primary object of this invention is to provide an improved packing of the type referred to that will effectively resist the action of heat when steam is the motivating medium, and which will maintain a substantially perfect fluid-tight seal between the coacting parts.

Another object is the provision of a packing which can be readily applied to a standard type of piston, for power reverse gears, with a minimum expenditure of time and labor.

Additional objects and advantages will become apparent as the following description of our invention proceeds, and for a more comprehensive understanding thereof reference will now be made to the accompanying drawing; wherein:

Fig. I is a face view of a locomotive power reverse gear piston embodying the present improvements.

Fig. II is an axial sectional view taken approximately on the plane designated by the arrows II---IIY in Fig. I; and

Fig. III is a fragmentary detail view of a sealing ring constituting a part of our improvedV packing.

Referring more in detail to the drawing, the 40 piston is comprehensively designated by the numeral 4, said piston comprising concentric components 5, 6, of conventional form, which are rigidly connected together by appropriate securing means I, passed through registering holes in interengaging flanges 8, 9; said flanges have spaced peripheral shoulders I0,'I I, respectively: while the flange 8 projects beyond, or is of greater diameter than, the flange 9, all in accordance with known practice and forming no part of this invention. Y

The packing with which the present improvements are more particularly concerned comprises a bull ring I2 and a follower ring I3, both of which are accurately machined to t the respective shoulders I, II, as well as being of a diamas by countersunk-screws registering holes i5, It in the flange B, an abut- 5 eter to ensure a free working iit in the cylinder, not shown, in which the piston t operates. To one of the shoulders II, for example, we secure EL3 passed through ting spacer-ring or annulus I'I, said screws engaging, at their ends I 8, in correspondinglythreaded holes I9 in the bull ring I2. Thus it will be seen that the parts I3, 8, I'I and I2 jointly afford a circumferential groove to receive a l0 sealing ring 2t which has a tcngue-and-groove split 2l, Fig. III. This sealing ring 20 is ofV an external diameter, when fully contracted, to snugly t the cylinder, not shown, in which it operates; while it has an internal diameter such 15 as to provide an annular interval therebetween and the bottom of the circumferential groove aiforded by the parts 8 and I'l aforesaid, and into said interval we insert suitable soft resilient packing-material 22.

On its inner face the follower ring I3 has a circular recess 23 to accommodate a freely-tting expander ring 24, preferably of the rightangled or L-shaped radial cross-section shown, so that the one portion can enter the interval 25 containing the packing-material 22, while the other portion provides a wider surface against which a. number of helical'springs 25' engage and exert compression-pressure at intervals around the follower ring I3. These springs 25 are held 30 in compression by hollow keeper-screws 26, and they serve to yieldingly urge the expander ring 24 laterally against the packing-material 22, in an obvious manner. At this juncture it is to be noted that the countersunk screws I4 serve 35 to hold the parts 3, I'I and I2 together, while the sealing ring 20 and packing-material 22 are applied, prior to placement of the follower ring I3 with the expander ring 24 in position. The follower ring I3 is thereupon secured by means 40 of screw-studs 2l engaged at their one ends in the bull ring I2 and clinched over at 28; said screw-studs passing through registering holes 29 in the spacer ring I'I, piston flange 8, and

l follower ring I3, and being engaged by cap nuts 45 30 at their outer ends, to hold the assembled units of the packing in proper relation.

Interposed between the inner faces of the bull and follower rings I2, I3, and the contiguous 50 surfaces of the spacer ring II and piston intervening flange 8, are suitable material gaskets v3l which prevent leakage of the motivating medium past the mutually contacting surfaces of the packing as a whole; while similar material 55 Washers 32 below the cap nuts 30 serve a similar purpose with respect to the stud holes 29.

From the foregoing description it will be readily seen that the fioatingly-supported ring not only ensures an effective fluid-tight seal between the piston 4 and cylinder wall in which it operates; but that said ring also serves to support the weight of the piston assemblage, with incidental protection of the bull and follower rings l2, I3 from early damage in use due to irregularlties developing in the associated piston crosshead and guides, not shown.

Having thus described our invention, we claim:

l. The combination with a piston body, having spaced shoulders separated by an intervening flange, of a bull ring seating on one of the shoulders and secured to the intervening ange with interposition of a spacer annulus; a follower ring seating on the other shoulder; said bull and follower rings, as well as the peripheral surface of the intervening flange and spacer annulus, jointly forming a circumferential groove; a split sealing ring in the circumferential groove; compressible packing-material filling an annular interval between the inner surface of the sealing ring and the bottom of the groove aforesaid; an expander ring 'disposed within a circular recess at the inner face of the follower ring and bearing laterally against the packing-material; circumferentially-spaced s p r i n g s operative against the expander ring to compress the packing material and thereby maintain the sealing ring expanded in fluid-tight contact with the Wall of a cylinder; means intermediate the inner faces of the bull and follower rings and the contiguous surfaces of the spa-cer ring and intervening flange aforesaid to prevent leakage past the mutually contacting surfaces of the packing as a whole; and means holding the several parts in assembled relation.

2. The combination with a piston body, having spaced angular shoulders separated by an intervening flange, of a bull ring seated on one of the angular shoulders and secured to the flange aforesaid with interposition of a spacer annulus; a follower ring seating on the other angular shoulder; said bull and follower rings, as Well as the intervening ange outer surface with that of the spacer annulus, jointly forming a circumferential groove; a split sealing ring fitting in the circumferential groove with provision of an annular interval between its inner surface and the bottom of the circumferential groove; compressible packing-material filling the annular interval; an expander ring freely accommodated in a circular recess in the inner face of the follower ring and bearing laterally against the packing material; a series of circumferentially-spaced helical springs operative upon the expander ring to effect constant compression of the packing-material and thereby maintain the sealing ring expanded in fiuid-tight contact against the surface with which it coacts; and means securing the several parts aforesaid in assembled relation.

3. The combination of claim 2 wherein the expander ring is of right-angled or L-shaped cross-section radi-ally.

4. The combination of claim 2 wherein the sealing ring is provided with a tongue-and-groove split.

RALPH A. LIGHT. JOSEPH W. PRICE, Jn. 

